JPanel frames

HelloApp.java

package example;

import javax.swing.*;
import java.awt.*;
import java.lang.reflect.InvocationTargetException;
import java.net.URL;

public class HelloApp {
   private final JLabel videoLabel;

   public static void main(final String[] args) {
      EventQueue.invokeLater(() -> {
         final HelloApp window = new HelloApp();
      });
   }

   public HelloApp() {
      final JFrame frame = new JFrame("MULTIPLE-TARGET TRACKING");
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      frame.setResizable(false);

      final int width = 800;
      final int height = 500;
      frame.setBounds(0, 0, width, height);
      frame.setLayout(new BorderLayout());

      // Show the frame at the center of the screen
      frame.setLocation(
         (int) (0.5 * Toolkit.getDefaultToolkit().getScreenSize().width - width / 2),
         (int) (0.5 * Toolkit.getDefaultToolkit().getScreenSize().height - height / 2)
      );
      frame.setVisible(true);

      final JPanel panel = new JPanel(new BorderLayout());
      frame.getContentPane().add(panel, BorderLayout.CENTER);

      videoLabel = new JLabel();
      panel.add(videoLabel, BorderLayout.CENTER);

      final JButton startButton = new JButton("START / REPLAY");
      startButton.addActionListener(event -> {
            // Frame processing should run in a separate (non-EDT) thread to avoid freezing the UI.
            // To spawn a thread you can use a bare Thread, or look at ExecutorService.
            //
            // Also remember not to press the button more than once, or multiple threads
            // will be updating the shown image
            final Thread thread = new Thread(() -> {
               try {
                  playVideo();
               } catch (final InterruptedException | InvocationTargetException ex) {
                  ex.printStackTrace();
               }
            });

            thread.start();
         }
      );

      panel.add(startButton, BorderLayout.PAGE_START);
   }

   private void playVideo() throws InterruptedException, InvocationTargetException {
      // Loop to showcase how the images change inside the JLabel
      while (true) {
         for (int i = 1; i < 6; i++) {
            // Here we process the frame.
            // Replace this with whatever you need to do
            final URL resource = getClass().getResource("/img" + i + ".jpg");

            // Update the shown image using the EDT thread, otherwise an exception will be thrown
            EventQueue.invokeAndWait(() -> {
               final Icon image = new ImageIcon(resource);
               videoLabel.setIcon(image);
            });

            // Simulate 20 FPS, to be removed
            Thread.sleep(50);
         }
      }
   }
}